Method for making a bearing having a self-lubricating surface coating

ABSTRACT

Methods for making a bearing are disclosed, wherein the bearing includes a substratum and a self-lubricating surface coating composition. The self-lubricating surface coating composition further includes at least one cured thermosetting acrylate and at least one phenolic resin. Methods includes the step of disposing the self-lubricating surface coating composition onto the substratum.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Pat. No. 9,156,059 B2 entitled“NOVEL SELF-LUBRICATING SURFACE COATING COMPOSITION,” having a prioritydate of May 16, 2011, the disclosure of which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

This invention relates generally to the field of self-lubricated surfacecoatings and especially to bearings that consist of a substratum and aself-lubricating surface coating composition adhered to at least aportion of the substratum.

BACKGROUND OF THE INVENTION

Self-lubricated bearings using polytetrafluoroethylene (PTFE) as asliding surface have been in use in the aerospace industry since the1960's according to U.S. Pat. No. 4,666,318 (hereinafter, the 318patent). The 318 patent teaches that thin films of woven PTFE bearingsurfaces are frequently reinforced with sintered bronze and textileyarns such as glass, graphite fibers, or high strength organic yarns ofrelatively high melting point. Woven structures are usually infused withresin systems such as phenol formaldehyde, epoxies or cyanoacrylates tobind the sliding surface into a dense structure. The 318 patent goes onto teach improved bearings using a reinforced low-friction plasticelement consisting of PTFE having a sliding surface and a counterfacewith a low surface roughness and high hardness.

U.S. Pat. No. 3,996,143 (hereinafter, the 143 patent) describes abearing surface consisting of a cured mixture of an acrylatecomposition, a particulate solid lubricant, and organic or inorganicfillers. The bearing surface can be applied by conventional techniquessuch as spraying, brushing, or dipping. The bearing surface adheres tothe substrate and can be built up to any thickness. In addition, thebearing surface conforms easily to the shape of the substrate beingcoated, can readily be produced in various thicknesses, often can bemachined to size, and as such has significant advantage over materialspreviously employed such as self-lubricating fabrics.

U.S. Pat. No. 4,053,665 teaches a molded bearing assembly with onesurface coated by a cured mixture of a curable acrylate composition andparticulate PTFE. In addition, U.S. Pat. No. 6,180,574 teaches aself-lubricating liner for bearings which includes a curable acrylatecomposition and a solid lubricant such as PTFE.

United States Patent Application Publication 2009/0275685, teaches abearing having a surface and a self-lubricating surface coatingcomposition including a curable acrylate composition having a metallicacrylate compound.

These and other works have advanced the self-lubricated bearing fieldand in particular the use of cured, self-lubricating acrylate surfacecompositions. These self-lubricating acrylate surface compositionsimpart the bearing with many desirable processing advantages and arebecoming increasingly important. Still there exists a need for improvedbearings with conformable and machinable, self-lubricating surfaces forenhanced service life and improved performance.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a method for making abearing having a self-lubricating surface coating. Briefly described,the present invention is directed to a method for making a bearing,wherein the bearing has a substratum and a self-lubricating surfacecoating composition. The self-lubricating surface coating compositionhas at least one cured thermosetting acrylate and at least one phenolicresin. The method includes the step of disposing the self-lubricatingsurface coating composition onto the substratum.

A second aspect of the present invention is directed to a method formaking a bearing. The bearing includes a substratum and aself-lubricating surface coating composition, wherein the methodincludes the steps of disposing an uncured self-lubricating surfacecoating composition onto the substratum, wherein the self-lubricatingsurface coating composition further includes at least one thermosettingacrylate and at least one phenolic resin, and curing theself-lubricating surface coating composition to solidify the compositionand adhere the composition in place.

Briefly described, a third aspect of the present invention is directedto a method for making a bearing, wherein the bearing has a substratumand a self-lubricating surface coating composition. The method includesthe step of disposing a cured self-lubricating surface coatingcomposition onto the substratum, wherein the self-lubricating surfacecoating composition further includes at least one thermosetting acrylateand at least one phenolic resin.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the invention can be better understood with reference tothe following drawings. The components in the drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the present invention. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 illustrates a first exemplary embodiment of the invention showinga bearing substratum and a self-lubricating surface coating.

FIG. 2 illustrates a second exemplary embodiment of the invention wherethe self-lubricating surface coating composition has cured acrylate andphenolic components arranged in a layered structure upon the bearingsubstratum.

FIG. 3 is a cross section of a journal bearing having the structure ofFIG. 2.

FIG. 4 illustrates a third exemplary embodiment of the invention havinga layered self-lubricating surface coating on a bearing substratum.

FIG. 5 illustrates a fourth exemplary embodiment of the invention wherethe self-lubricating composition is a cured thermosetting acrylatedisposed upon a cured mixture of phenolic resin and thermosettingacrylate, where the cured mixture of phenolic resin and thermosettingacrylate is coated on a bearing substratum.

FIG. 6 illustrates a fifth exemplary embodiment of the invention where acured mixture of phenolic resin and thermosetting acrylate is coated onthe substratum with a different cured mixture of thermosetting acrylateand phenolic resin coated as the top layer.

FIG. 7 illustrates a bushing-cylindrical holder assembly in accordancewith exemplary use of the present invention.

FIG. 8 illustrates a cross-sectional view of the bushing-cylindricalholder assembly of FIG. 7.

FIG. 9 is a graphical representation of wear versus cycles ofoscillation of a self-lubricated liner provided by the presentinvention.

DETAILED DESCRIPTION

The present invention provides self-lubricated bearings containing asubstratum and self-lubricating surface coating composition disposedthereon wherein the self-lubricating surface coating composition furthercontains at least one cured thermosetting acrylate and at least onephenolic resin. The phenolic resin preferably contains a mixture ofphenolic resin and polyvinyl formal resin. The present invention alsoprovides the self-lubricating surface coating composition and severalmethods of making bearings in accordance with the present invention.

The self-lubricated bearings can be any type and have a surface orsubstratum of any geometry. Some examples of the more common bearingtypes are plain journal bearings, flanged journal bearings, sphericalbearings, track rollers, roller bearings, loader slot bearings, flatplates, earthquake bearing constructions for buildings, roads, bridges,tunnels, and other bearings. A bearing of the invention is used in anyconstruction where two surfaces are in contact with each other, undersome load, and one surface is free to move relative to the othersurface, wherein a self-lubricating composition contains at least one ofthe two surfaces and is disposed on a substratum over at least part ofthe area where the two surfaces are in movable contact. The surfaces canbe of the same or different geometries relative to each other. Theself-lubricating composition functions to reduce friction and wearbetween the two surfaces.

Several representative bearing embodiments are shown in the figuresprovided herein to illustrate the present invention and differentexemplary embodiments of the present invention. It should be noted thatthe figures herein do not represent a comprehensive list and as such arenot intended to be limiting of the invention in any way.

A first exemplary embodiment of the invention is depicted in FIG. 1. Asubstratum 1 is illustrated as flat for simplicity, but it may be anygeometry. A self-lubricating surface coating composition 2 a is disposedon the substratum 1 and contains a cured mixture of thermosettingacrylate and phenolic resin. A counter surface of the bearing is notshown for simplicity. The cured mixture of thermosetting acrylate andphenolic resin 2 a adhere and conform to the geometry of the substratum1 and can be any thickness relative to the substratum 1. Theself-lubricating surface coating composition 2 a is depicted as coveringall of the substratum 1, but it also may cover only a portion of thesubstratum 1.

FIG. 2 illustrates a second exemplary embodiment of the invention wherethe self-lubricating surface coating composition has cured acrylate andphenolic components arranged in a layered structure upon the bearingsubstratum. Referring to FIG. 2, the self-lubricating surface coatingcomposition is a layered structure containing a cured thermosettingacrylate 2 b adhered to the top of phenolic resin 3 a. The phenolicresin 3 a is adhered to the substratum 1.

FIG. 3 is a cross sectional view of a journal bearing (or sleevebearing) having the layered structure of FIG. 2. As with all figures,the relative thicknesses of the various layers are not drawn to scale inan effort to provide a clearer depiction of the embodiment.

FIG. 4 illustrates a third exemplary embodiment of the invention havinga layered self-lubricating surface coating on a bearing substratum.

The layered self-lubricating composition contains a cured mixture ofthermosetting acrylate and phenolic resin 2 a adhered to phenolic resin3 a. As shown by FIG. 4, the phenolic resin 3 a is adhered to thesubstratum 1.

Alternatively, in accordance with a fourth exemplary embodiment of theinvention, as shown by FIG. 5, the self-lubricating composition may be acured thermosetting acrylate 2 b disposed upon a cured mixture ofphenolic resin and thermosetting acrylate 3 b. The cured mixture ofphenolic resin and thermosetting acrylate 3 b covers at least a portionof the substratum 1.

FIG. 6 illustrates a fifth exemplary embodiment of the self-lubricatedbearing. As shown by FIG. 6, a cured mixture of phenolic resin andthermosetting acrylate 3 b is covering the substratum 1, while adifferent cured mixture of thermosetting acrylate and phenolic resin 2 ais the top layer.

The self-lubricating surface layers 2 a, 2 b, 3 a, 3 b in the figuresmay be any thickness. Typically the total self-lubricating compositionthickness is less than 0.100 inches thick, and more typically less than0.050 inches thick although it may be applied to the substratum 1 inthicknesses of 0.25 inch or greater. It should be noted that in somepreferred embodiments, self-lubricating surface layers 3 a and 3 b areabout 0.002 inch in thickness or less. In addition, the self-lubricatingsurface layers 3 a and 3 b may be about 0.001 inch thick or less.

Several methods of making the presently disclosed bearings are alsoprovided by the present invention. The self-lubricating composition maybe disposed upon the substratum 1 in a fluid state by spraying,brushing, rolling, spinning, molding, coating, or some combination ofthese, and then curing to solidify the composition and adhere thecomposition in place. These processes are applicable to the bearings ofthe invention depicted in all of the figures. One having ordinary skillin the art would also appreciate that other methods of deposing may beused.

Alternatively, a portion of the self-lubricating compositions (2 a or 2b, whichever is applicable) of FIGS. 2-6 may be molded or otherwiseformed in shape and cured apart from the substratum 1. Layer 3 a or 3 b,whichever is applicable, is then deposited on the substratum 1 in afluid state by spraying, brushing, rolling, spinning, molding orotherwise coating. Deposited layer 3 a or 3 b, whichever is applicable,may optionally then be dried, if it contains a solvent. The hardenedshape formed independently is then conjoined with the coated substratumand post-cured to make a self-lubricating bearing of the invention.

It has surprisingly been found, during the course of this work, that amolded or otherwise formed, cured shape containing self-lubricatingsurface component 2 a and/or 2 b may also be used as a bearing, in andof itself for certain applications, without needing to be bonded to anysubstratum 1. The best method for a making a particular bearing of theinvention will depend upon the bearing surface geometry, size, intendeduse and number of bearings required.

The bearing substratum 1 in FIG. 1 may be any material including, butnot limited to, aluminum, steel, titanium, stainless steels, metalalloys, composites, polymer alloys, ceramics, or any combination ofthese. The substratum 1 is used in movable contact with another surface,which is not illustrated in FIG. 1.

In order to optimize overall bearing performance, the bearing substratum1 finish is prepared prior to applying the self-lubricating surfacecoating composition. The first step of the substratum finish preparationis to roughen the substratum 1 surface to obtain a specific averageroughness or Ra. This roughness can be achieved by a variety of knownmethods such as, but not limited to: grit blasting with abrasive media;chemical etching: plasma or electrical discharge etching: mechanicalroughening to impart a random or specific roughness pattern; and othermethods. Any surface roughness can be used but it is preferred to havean Ra value greater than 25 micro-inches as measured with a profilometerusing a 0.030 inch cutoff. While not necessary, it is more preferred tohave the Ra value above 100 microinches, and in some applications it iseven more preferred to have the Ra greater than 150 microinches.

Once the desired substratum roughness is attained the substratum iscleaned to free it of oils, greases and other contaminants and may alsooptionally be etched, deoxidized, passivated and the like, dependingupon known methods of surface preparation for the particular substratumcomposition.

The acrylate may be any acrylate monomer or oligomer. The acrylate maybe acid or ester functionalized or combinations thereof. There aremyriad acrylate monomers and oligomers that are useful in the inventionand some representative, but non-limiting examples are supplied by theSartomer Company of Exton, Pa. Monomers and oligomers may be chosen andused alone or mixed together to tailor end use properties such as resinviscosity, abrasion resistance, cross link density, chemical resistance,reactivity, temperature resistance, hardness, adhesion, and other useproperties.

The phenolic resin may be any phenolic resin. The phenolic resin may bea resole or novolak or a combination thereof. The phenolic resin ispreferably a vinyl phenolic resin, which is a combination of a phenolicresin with a polyvinyl formal resin (sometimes also referred to aspolyvinyl formal). Polyvinyl formal is a member of the polymer familyand includes, but is not limited to, polymers formed from polyvinylalcohol and formaldehyde as copolymers with polyvinyl acetate. Anotherdescription of polyvinyl formal is modified polyvinyl acetal resins. Anexample of a vinyl phenolic resin is MVK-7000 obtained from the MaverickCorporation of Blue Ash, Ohio. The phenolic resin may be a thermosettingphenolic resin or it may be a thermoplastic phenolic resin.

Fillers, reinforcements, and modifiers may be added to the acrylateself-lubricating compositions of the invention in order to meet specificend use application requirements. Some typical examples of fillers arefiberglass, fiberglass fabrics, carbon fiber, carbon fiber fabrics,mineral fibers, polymer fibers, clays, mica, glass flake, mineralfillers, carbon black, colorants, aramid fibers and fabrics, variouscombinations of these and the like.

Lubricants may be added to the self-lubricating surface coatingcomposition to reduce the coefficient of friction and improve wearresistance. Some examples of lubricants include, but are not limited to,polytetrafluoroethylene powders, polytetrafluoroethylene fibers,polytetrafluoroethylene film, activated polytetrafluroethylene fibers,polytetrafluoroethylene lubricants with enhanced wettability whichinclude but are not limited to activated polytetrafluoroethylene fibers,other fluoropolymer based lubricants, graphite, molybdenum disulfide,tungsten disulfide, hexagonal boron nitride, hydrocarbon oils, siliconefluids and polymers, perfluoropolyethers, and other similar lubricants.

Thixotropes may be added to the self-lubricating composition of theinvention. Fumed silica is a useful thixotrope. It has been determinedthat synergistic combinations of fumed silica with modified ureasprovide surprisingly good thixotropic performance with half or less theamount of silica typically required.

Curing can be done by any method including heat, light, electron beam,or another method. Standard thermal initiators and photo-initiators areknown in the art and can be added to facilitate curing of theself-lubricating composition. Specific examples of known thermalinitiators include, but are not limited to, organic peroxides. Variousorganic peroxides are available from several sources, for instance theArkema Company or Sigma Aldrich. Examples of peroxides suitable for usein the present invention include, but are not limited to, benzoylperoxide, cumenehydroperoxide, methyl ethyl ketone peroxide, andcombinations thereof. Different peroxides initiate curing at differenttemperatures and rates. The peroxides are often chosen based onprocessing and handling considerations. In some cases it may beadvantageous to use two or more peroxides to initiate curing atdifferent temperatures or to include a peroxide and photo-initiator tocombine ultraviolet light and thermal curing.

Benzoyl peroxide (Luperox® A98) is an effective peroxide useful in theinvention. The amount of initiator used is an important factor affectingthe pot life of the acrylate composition. The exact acrylate compositionchosen is also a factor affecting pot life as different acrylates reactat somewhat different rates with the same amount and type of peroxide.

The self-lubricating surface coating composition is most effectivelyprepared by combining or compounding the ingredients in standard mixerssuitable for mixing acrylate, silicone or epoxy-type compositions.Typical mixers useful for preparation of the compositions includeplanetary mixers, high shear mixers, and other mixers. The ingredientsmay be combined all at once or in any order. The phenolic resincomponent may be added along with the other ingredients to the acrylatecomposition. The phenolic resin component may optionally be addedindependently to the bearing substratum before combining the acrylatecomposition with the substratum. The phenolic resin component mayoptionally be added to the acrylate composition and the same or adifferent phenolic resin component added to the bearing substratumbefore adding the acrylate containing phenolic resin composition to thesubstratum.

Depending upon the exact formulation, type of mixer, and volume mixed itmay be advantageous to combine the acrylate and solid fillers either inparts or all at once to promote the most effective mixing. The sequenceof filler and additive addition and mixing, as well as mixer speeds andconditions are understood and manipulated by those skilled in thecompounding art to control dispersion as well as to manage shear heatingthat occurs during the mixing process.

It is desirable to have the mixer equipped with capability to mix theingredients under vacuum in order to properly wet and disperse thefillers or fibers as well as to reduce the oxygen concentration in thefinal mixture before applying the self-lubricating surface coatingcomposition to the bearing substratum. The final oxygen concentration inthe acrylate composition is controlled by the level of vacuum applied.Oxygen concentration is an important parameter that affects pot life ofthe mixture as well as quality of the self-lubricated bearings of theinvention.

The self-lubricating surface coating composition in a fluid form may bedisposed on the bearing substratum by a variety of methods (see above).The self-lubricating acrylate composition is then cured to solidify it.At this point in the process the bearing containing a substratum andself-lubricating surface coating composition may be: used as is;machined to size; post-cured; post-cured then machined; or machined thenpost-cured then machined again. The exact sequence depends upon thebearing design and end use requirements. Post-curing has usually beendone at a higher temperature than that used for the initial cure,however this is not a requirement of the invention. Post-curing canfurther improve the self-lubricated bearing's performance. In someembodiments with certain thermosetting phenolic resins, thethermosetting phenolic resin component does not cure completely untilthe post-cure process.

The following provides non-limiting examples of the above-mentioned. Itshould be noted that the following is provided for exemplary purposesand is in no way intended to limit the present invention and/ordisclosure.

First Example Thermosetting Self-Lubricating Surface Coating CompositionPreparation

Ingredients (1) and (2) were premixed and heated gently to about 120° F.for about 2 hours to aid dissolution. The resulting solution was allowedto cool to room temperature and the remaining thermosetting acrylateingredients were added sequentially with mixing.

Thermosetting Acrylate & Polymer Ingredients Parts by Volume (1)Tricyclodecane dimethanol diacrylate 63.6 (2) Tris (2-Hydroxyethyl)Isocyanurate Triacrylate 23.1 (3) Benzoyl Peroxide 1.2 (4) Modified Urea1.0

Reinforcing fillers, lubricants and viscosity modifiers as listed belowwere then mixed into the thermosetting acrylate mixture until welldispersed.

Remaining Ingredients Parts by Volume (5) Glass Fibers 13.2 (6)Activated PTFE Fiber 23.6 (7) PTFE Powder 4.5 (8) Silica 0.7

The combined thermosetting self-lubricating composition was held undervacuum (28 in mercury) with intermittent mixing for three hours. Aportion of the mixture was then poured into a pneumatic dispensercartridge.

Aluminum bushings with a 0.5 inch bore meeting Aerospace Standard PartNumber M81934/1-08A12 were prepared by standard methods with a surfaceroughness (Ra measured with a 0.030 inch cutoff) greater than 150 microinches. The surface was then ultrasonically cleaned with an alkalinecleaner and the surface etched with Oakite™ Deoxidizer LNC according tostandard industry methods.

Second Example (Comparative) Preparation of a Bearing withSelf-Lubricating Thermosetting Acrylate

Two half inch bushings 4 were placed end-to-end with washers 5 cut from0.012 inch thick polytetrafluoroethylene fiberglass sheet in an aluminumcylindrical holder 6 as shown in exploded view in FIG. 7 and as a crosssectional assembly in FIG. 8. The washer's (5) internal diameter matchedthe internal diameter of the self-lubricating liner once it is disposedon the bushing 4 surface. The bushing-cylindrical holder assembly wasthen placed into a variable speed lathe using a steel Collet. The lathewas equipped with an open passage and nitrogen gas was flowed at 8.7liters per minute through the lathe and bushing-cylindrical holderassembly (FIG. 8). The bushing-cylindrical holder assembly was thenrotated at 38 rpm. A 0.030 inch thick layer of the self-lubricating,thermosetting composition (described above) was deposited by applying0.930 grams uniformly over the internal bushing surface from an EFDcartridge. The bushing-cylindrical holder assembly rotational speed wasthen increased to 3000 rpm over 60 seconds. Heated air was blown on thebushing-cylindrical holder assembly surface to heat the surface to about240° F. over 5 minutes. After ten minutes the spinning speed wasdecreased to 300 rpm and the surface temperature gradually increased toabout 248° F. over the next 20 minutes. The bushing-cylindrical holderassembly was then cooled and bushings removed.

Third Example Preparation of a Bearing with Self-Lubricating SurfaceCoating Composition Containing at Least One Cured Thermosetting Acrylateand at Least One Phenolic Resin

The internal surfaces of two aluminum bushings, prepared as describedabove in the Comparative Example, were brush coated by hand with vinylphenolic resin and air dried at 200° F. for 30 minutes. The driedbushings had about a 0.0005-0.001 inch thick layer of vinyl phenolicresin after drying.

The vinyl phenolic resin coated bushings were placed end-to-end into thealuminum cylindrical holder. The bushing-cylindrical holder assembly wasthen placed into a variable speed lathe using a steel collet as in theComparative Example (above). The lathe was equipped with an open passageand nitrogen gas was flowed through the lathe and pot chuck at 8.7liters per minute. The pot chuck was then rotated at 37 rpm. A 0.030inch thick layer of the self-lubricating, thermosetting composition wascreated by applying 0.930 grams uniformly over the internal bushingsurface from an adhesive dispenser cartridge. An example of an adhesivedispenser cartridge that may be used in accordance with the presentinvention is available commercially from Nordson EFD, LLC of EastProvidence, R.I. The pot chuck speed was then increased to 3000 rpm over60 seconds. Heated air was blown on the pot chuck surface to heat thechuck surface to about 240° F. over 5 minutes. After ten minutes thespinning speed was decreased to 300 rpm and the surface temperaturegradually increased to about 248° F. over the next 30 minutes. The chuckwas then cooled and the bushings with the cured acrylate andvinyl-phenolic surface composition removed.

It has generally been observed in these studies that theself-lubricating surface coating composition of the invention containingcured thermosetting acrylate and at least one phenolic resin requiresslightly higher temperatures and/or longer times to cure to a solid massthan comparative example thermosetting acrylate without phenolic resincomposition.

Machining & Post Curing Example 2 and Example 3 with Self-LubricatingLiners

The approximately 0.030 inch thick, hardened (cured), self-lubricatingsurface coating composition linings in the bushings were then machinedto 0.012 inches. The machining was done on a lathe, without coolant,using a carbide insert with a 0.015 inch nose radius at 2700-4400 inchesper minute surface speed with a feed rate below 1.5 inches per minute.The bushings with machined, self-lubricating lining composition werethen slid onto aluminum rods with a locational clearance fit.

The aluminum rod-bushing assembly was then placed into a forced aircirculating oven to post-cure the self-lubricating composition. The ovenwas heated from ambient temperature to 340° F. at 2° F. per minute, thenheld at 340° F. for twenty hours and cooled back to room temperature at5° F. per minute.

The bushings were removed from the aluminum rod and the self-lubricatingcomposition linings were then machined (as described above) to a finalsize of 0.010 inches thick for High Temperature Oscillation Testing.

High Temperature Oscillation Testing Machined & Post Cured Example 2 andExample 3 Bearings with Self-Lubricating Liners

Two pieces of each bushing (or sleeve bearing) were subjected to thehigh temperature oscillation under radial load test per AerospaceStandard Specification AS81934, paragraph 4.6.4 and 3.6.4.

Testing was accomplished using two custom made dynamic testing machines.Both machines are hydraulically loaded and have mechanically drivenoscillation mechanisms. The test sleeve bearings were installed in sucha way as to hold the sleeve bearing static while oscillating thehardened steel pin within the bore by a spindle mounted on rollerbearings. The bearings were heated to maintain a temperature of 325° F.during testing with the use of electrical resistance heaters controlledby an electronic heat controller. The thermocouple used to indicate testtemperature was located in a drilled hole in the bearing retentionhousing immediately adjacent to the loaded area of the sleeve bearing.

With a load applied to the sleeve bearing, and the bore pin oscillatingagainst the liner, the wear of the self-lubricated liner was monitoredby the use of mechanical dial indicators, 0.0001 inch measurableincrement, at each station. The testing machines were halted atconvenient intervals to take wear readings of the self-lubricated linerwhen appropriate. The wear readings of the self-lubricated liner wereplotted on an X-Y graph to give a graphical representation of wearversus cycles of oscillation (FIG. 9). Comparative Example—Bearings WithSelf-lubricating Thermosetting Acrylate Liners wore an average of 0.006inches in 27,000 cycles while the Bearings having a self-lubricatingsurface coating composition in accordance with the present invention,containing at least one cured thermosetting acrylate and at least onephenolic resin, required an average of 65,000 cycles to reach 0.006inches of wear. Therefore, the machined and postcured inventive Example3 bearings lasted, on average, 2.3 times longer than the machined andpostcured Example 2 bearings.

It should be emphasized that the above-described embodiments of thepresent invention are merely possible examples of implementations,merely set forth for a clear understanding of the principles of theinvention. Many variations and modifications may be made to theabove-described embodiment(s) of the invention without departingsubstantially from the spirit and principles of the invention. All suchmodifications and variations are intended to be included herein withinthe scope of this disclosure and the present invention and protected bythe following claims.

We claim:
 1. A method for making a bearing, wherein the bearingcomprises a substratum and a self-lubricating surface coatingcomposition, wherein the self-lubricating surface coating compositionfurther comprises at least one cured thermosetting acrylate and at leastone phenolic resin, wherein the method comprises disposing the phenolicresin on the substratum and disposing the thermosetting acrylate on thephenolic resin coated substratum.
 2. The method of claim 1, wherein thephenolic resin is a mixture of phenolic resin and polyvinyl formalresin.
 3. The method of claim 1, further comprising: drying the phenolicresin; and disposing the thermosetting acrylate on the dried phenolicresin coated substratum.
 4. The method of claim 1, further comprising:drying the phenolic resin; disposing the thermosetting acrylate on thedried phenolic resin coated substratum; and curing the phenolic resinand the thermosetting acrylic.
 5. The method of claim 1, wherein theself-lubricating surface coating composition further comprises alubricant selected from the group consisting of polytetrafluoroethylenefibers, polytetrafluoroethylene floe, polytetrafluoroethylene powder,graphite, molybdenum disulfide, tungsten disulfide, boron nitride,copper, talc, perfluoropolyethers, silicone fluids, oils, waxes, andcombinations thereof.
 6. The method of claim 1, wherein theself-lubricating surface coating composition further comprisesreinforcing fillers selected from the group consisting of glass fibers,carbon fibers, aramid fibers, wool fibers, polyester fibers, polymerfibers, mineral fillers, and combinations thereof.
 7. The method ofclaim 1, wherein said phenolic resin on said substratum comprises amixture of phenolic resin and thermosetting acrylate.
 8. The method ofclaim 1, wherein said phenolic resin on said substratum comprises amixture of phenolic resin and thermosetting acrylate and saidthermosetting acrylate disposed on said phenolic resin comprises amixture of thermosetting acrylate and phenolic resin.
 9. The method ofclaim 1, wherein the phenolic resin is disposed upon the substratum in afluid state.
 10. The method of claim 1, further comprising the step ofroughening the substratum surface prior to applying the phenolic resin.11. The method of claim 10, wherein roughening further comprisesimparting a random or specific roughness pattern to the substratumsurface by one of the group consisting of grit blasting with an abrasivemedia, chemical etching, plasma or electrical discharge etching, andmechanical roughening.